"He just needs to refine his breaking balls and work his two-seamer more," Ausmus said.
Lefties are hitting .364 off Ryan this season, while he has limited right-handed hitters to a .262 batting average.
He has given up one homer and two triples this season, all to lefties, including a two-run triple to Jacoby Ellsbury on Thursday night.
Hardy rejoins the Tigers after a solid stint with Toledo. He threw nine innings over 10 appearances with the Mud Hens, allowing one run, three hits and one walk. He has had more success against left-handed hitters than Ryan this season. Across 17 appearances in the Major and Minor leagues, he is holding them to a .120 batting average.
Hardy has made six appearances for the Tigers in 2016, allowing three runs in 7 1/3 innings. He has a 2.84 career ERA with the Tigers over parts of three seasons.
He appeared in 70 games in 2015 and went 5-3 with a 3.08 ERA.
Kyle Beery is a reporter for MLB.com based in Detroit.